Centralized traffic controlling system



April 21, 1936 N. D. PRESTON CENTRALIZED TRAFFIC CONTROLLING SYSTEM 2 Sheets-Sheet 1 Original Filed Aug. 51,- 1931 wm own H mum U25 IIIIIL April 21, 1936. N D E T N CENTRALIZED TRAFFIC CONTROLLING SYSTEM Original Filed Au fsl, 1951 2 Sheets-Sheet 2 Patented Apr. 21 1936 UNITED STATES CENTRALIZED TRAFFIC CONTROLLING SYSTEM Neil D. Preston, Rochester, N. Y., assignor to General Railway Signal Company, Rochester,

Application August 31, 1931, Serial No. 560,356 Renewed June 22, 1935 39 Claims.

This invention relates to systems for governing trafiic on railroads, and more particularly pertains to systems known as centralized traflic control systems. r

In a centralized traflic control system of the type contemplated by this invention, the switches and signals at various points along a railroad system throughout an extended territory, are placed under the control of an operator in a central control ofiice, in such a way that the operator may at will change the position of the switches, subject to automatic approach and detector locking circuits which prevent unsafe operation of any switch, and may also hold at stop any of the signals, or allow them to clear dependent upon the position of the associated switches, and also provided the location of trains makes it safe for such a signal to indicate proceed. In such a type system, it is desirable that the operator be fully and accurately informed of the movement of trains and of the operation of the switches and signals which he controls. For this purpose various indications are transmitted to the control oifice to show the presence or absence of trains on the various track sections and to show the operated positions of the various switches, signals and the like.

In accordance with this invention, the indications of the condition of a railroad track switch are transmitted to the; control oifice in the same Way asheretofore employed in systems of this type; but instead of displaying these indications directly, that is, just as last transmitted to the control oflice, it is proposed to provide a lamp, or equivalent means, to indicate'the correspondence between the operated position of a track switch in the field and the position of its control lever in the central control office. This indicating lamp is controlled by indications received from the field and by the position of the switch lever in the control ofiice,in such a way that the operator can easily and quickly tell the operated position of the track switch in question and its response to manual control. p g

Stated more specifically, in accordance with this invention, a correspondence lamp for each track switch, which lamp is normally dark, is illuminated whenever that track switch and its control lever are out of correspondence. Itis further proposed, that, if the operator moves the control lever for that switch to a new position out of correspondence therewith, the correspondence lamp will be illuminated to indicate such lack of correspondence and will be maintained illuminated irrespective of subsequent movement of the control level until a new indication or a repeated old indication has been received fromthe associated field station. This is accomplished by providing a stick relay to control the correspondence lamp which relay is picked up whenever the control lever is operated out of correspondence with its associated track switch, and is maintained energized until the indication storing relays in the control ofiice have received indications in accordance with the actual position of the track switch.

As a correspondence light is maintained illuminated in the control oifice during the operation of its track switch to a new position, it is then unnecessary to cause the communication system to transmit an indication of the unlocked condition of the track switch under normal operating conditions. Thus, the present invention further proposes to provide means in the field for automatically initiating the normally at rest system only when the track switch has been operated to a new extreme position. However, at times when the track switch does not follow its control lever due to jamming of the switch points, or some other reason, it becomes necessary for the op- 25 erator to check the indications so as to ascertain the exact conditions. The present invention under such circumstances provides that the system shall allow the operator to check or repeat the indications associated with a track switch whenever the routes over that track switch are at stop.

These characteristic features of the invention, thus briefly stated, will be explained more in detail in the following description of one embodiment of the invention; and various other characteristic features, functions and advantages of a system embodying this invention will be in part pointed out and in part apparent as the description progresses.

In the accompanying drawings, the invention has been shown applied to a single switch and its associatedsignals, such as used at one end of a passing siding, but it should be understood that the invention is not limited, as thus shown, to the control of one switch and its signals, but may be extended for any desired number of switches and signals, and may be readily applied to all ty s of track layouts.

In describing the invention in detail, reference will be made to the accompanying drawings, in which similar parts throughout the several views are designated by similar reference characters provided with distinctive exponents, and in which:--

Fig. 1 illustrates the apparatus and circuit arrangement provided for a typical control ofiice having indication means constructed and arranged according to the present invention;

Fig. 2 illustrates the apparatus and circuit arrangement employed at a typical field station for providing the information of the operated condition of a railroad track switch in accordance with the present invention, and adapted to be associated with the apparatus employed in the control ofiice.

For the purpose of simplifying the illustration and facilitating in the explanation, the various parts and circuits constituting the embodiment of the invention have been shown diagrammatically and certain conventional illustrations have been employed, the drawings having been made more with the purpose of making it easy to understand the principles and mode of operation, than with the idea of illustrating the specific construction and arrangement of parts that would be employed in practice. Thus, the various relays and their contacts are illustrated in a conventional manner, and symbols are used to indicate connections to the terminals of batteries, or other sources of electric current, instead of showing all of the wiring connections to these terminals.

The symbols (-1-) and are employed to indicate the positive and negative terminals respectively of suitable batteries, or other sources of direct current; and the circuits with which these symbols are used, always have current flowing in the same direction. The symbols (B-{) and (B) indicate connections to the opposite terminals of a suitable battery, or other direct current source which has a central or intermediate tap designated (CN) and the circuits with which these symbols are used, may have current flowing in one direction or the other depending upon the particular terminal used in combination with the intermediate tap (ON).

While certain features of the invention are. applicable to, and usable with any type of communication system for centralized trafiic control, whether obtained by direct line wire control or by some form of a selective type communication system, the specific embodiment of the invention illustrated has been shown in a form adapted for use with a selective communication system of the duplex coded type, shown and described in detail in the pending application of N. D. Preston, et al., Ser. No. 455,30e, filed May 24, 1930. Thus, before considering the structure and mode of operation of the parts constituting this invention, it becomes necessary to explain some of the features of this particular duplex coded type of communication system, insofar as material to an understanding of the present invention, reference being made to said prior application for other details of the structure and operation of such a duplex coded communication system not directly related to the features of this invention.

Communication part of the. system.The communication part of the centralized trafiic control system comprises a transmitting and receiving equipment located in the control office and interconnected with the transmitting and receiving equipments located at the various field stations by three line wires forming a series stepping and control circuit and a series message circuit, each of these circuits having a common return connection. In the drawings these three. line wires are designated l2, l3 and M. The series stepping and control circuit is completed over the stepping line wire I2 and the common return line wire M which are connected together at the last field station,

and includes a three position polar relay L in the line wire l2 at the control ofiice and at each of the field stations.

In the control office suitable means is provided for governing this stepping circuit and energizing it with time spaced impulses of particular polarities in accordance with the codes and the controls to be transmitted. These impulses as repeated by the line relays L, operate a stepping relay bank at the control oflice and at each of the field stations irrespective of the polarity of such impulses, While the polarity of the impulses determines the controls transmitted to the various field stations. The apparatus for governing the cycles of time spaced impulses includes a cycle controlling relay CC which closes the stepping circuit at the beginning of each cycle of operation and opens the stepping circuit at the end of each such cycle. An impulsing relay IR is employed to time space the impulses applied to the stepping circuit, with the polarity of these impulses determined by a code sending relay CS which is energized or deenergized on the successive steps in accordance with the code and controls to be. transmitted, as set up by the code determining relay CD and the position of the control levers associated with that station.

The series message line circuit is completed over the message line wire i3 and the common return line wire M which are connected together at the last field station, and includes a message line relay M at the control office and at each field station in the line wire l3; and also a contact operated by a pulsing relay P at each of the field stations.

This series message circuit is normally energized by a battery in the control ofiice, and is left energized or is deenergized on each step (marked off by one energization and one deenergization of the stepping circuit) in accordance with the contacts on the relays P, one at each field station. In other words, if all of the P relays are deenergized on a particular step, the message circuit remains energized for that step; but, if one or all of the P relays are energized on a particular step, the message circuit is deenergized. This energization and deenergization of the message circuit on each step is of course repeated by the relays M, which serve to register a particular station in the control ofiice and to transmit the indications from that particular station.

Although the particular field station in this type of system, which is registered in the control ofiice for a cycle of operation, is determined in accordance with the relation of its code call to the code calls of other stations which may be endeavoring to be registered at the same time, such features do not effect the principles of the present invention and need not be explained.

The transmission of controls from the control ofiice to a selected station, and/or the transmission of new indications, if any, from that station or some other station back to the control office takes place during the execution periods of a predetermined number of steps resulting from the successive energizations of the stepping circuit at time spaced intervals, this being conventionally termed an operating cycle. In the beginning of such an operating cycle, a slow acting relay SL in the control ofiice (see Fig. l) and a similar relay SL at each field station (see Fig. 2) are energized, and are sufiiciently slow acting to be maintained energized between successive impulses throughout the operating cycle. The application of the successive impulses of a cycle. to the stepping circuit causes the operation of'the stepping relays at the control oflice and at each field station, one step for each impulse irrespective of the polarity of the impulses; while an impulse storing relay IS of the polar magnetic stick type is actuated in accordance with the polarity at each of the field stations. The time period or spaces between the successive impulses of a cycle are conveniently termed execution periods during which the controls are executed, as stored by the relays IS, and during which the indications are executed, as indicated by the relays M. This prevents the overlapping of controls or indications between the successive steps. These execution periods are marked off by quick acting line repeating relays (not shown) in the control office and at each field station.

The system is normally at rest, but is set into a cycle of operation by the operator to establish communication with a selected station by actuation of a starting button SB (see Fig. 1) associated with the control levers for that station, or may be set into operation independently of the operator whenever a change takes place at any one of the field stations requiring the transmission of indications.

The operating cycle of this duplex coded communication system consists of a station selecting part and a control transmitting part. During the station selecting part of the operating cycle, the station to receive controls from the control office is selected in a manner explained in detail in said application of N. D. Preston et al. above mentioned, resulting in the energization of the relays SO and TR at the desired station (see Fig. 2). Also, during this station selecting part of the operating cycle, one of the several stations having new indications to transmit may be registered in the control office, this condition being manifested by the energization of a station registration relay in the control oifice such as relay C (see Fig. 1), and the energization of the relays SI and TR at the corresponding field station (see Fig. 2).

During the control transmitting part of the operating cycle, a series of stepping relays in the control ofiice, such as relays d, e and f (see Fig. 1') and a similar series of stepping relays at the station selected for outgoing controls and/or at the station registered at the control ofiice for incoming indications, such as relays 4, 5 and 6 (see Fig. 2), are energized sequentially one at a time in synchronism by the impulses applied to the stepping circuit; and on each of these successive steps either one of two distinctive controls and/or two distinctive indications may be simultaneously transmitted from or to the control office, all in a manner explained in said application of N. D. Preston et a1., Ser. No. 455,- 304, above mentioned.

Although any one of a plurality of field stations may be selected for the transmission of controls and/or indications during any particular operating cycle, it is not necessary for the purpose of understanding the present invention to explain how the stations are selected and the controls and/or indications are transmitted in this duplex coded type of communication system; but it is sufficient to note that such transmission of controls and/or indications results in the positioning of the contact fingers of two position polar relays in one extreme position or the other, in correspondence with the position of their controlling contacts. Each of these two position polar relays is of the dead beat or magneticstick type, so that its contact fingers are held in the positions to which they were last operated by means of a permanent magnet or other equivalent means.

Keeping in mind this general organization of the complete communication system. contemplated in connection with the particular embodiment of the invention illustrated, and particularly the fact that controls and indications may be transmitted to and from any one of several field stations; one at a time during successive operating cycles, consideration may now be given to an explanation of the present invention as if it were applied to only one station, as shown in the accompanying drawings.

Control ofiice equipment.The control ofiice (see Fig. 1) includes a control machine having a group of control levers for. each field station, a miniature track layout corresponding in every way to the actual track layout in the field, and various indicating lamps or equivalent devices, together with apparatus and circuits to accomplish proper functioning of the system. Fig. 1 illustrates diagrammatically a portion of such a control machine for one track switch, a cross over or the like.

This apparatus for one track switch at a field station comprises a switch machine control lever SML, a signal control lever SGL, a self restoring starting button SB and a correspondence lamp COL. The movement of the switch machine lever SML to one extreme position or the other results in the normal or reverse control of the corresponding track switch at the corresponding field station, through the medium of the communication system; and the movement of the signal control lever SGL from the intermediate or vertical position shown, corresponding to signals at stop, to the right or left clears a signal for trafiic over the associated track switch in east or west bound direction respectively. 7

The starting button SB, when momentarily actuated by the operator, results in the energization of a storing relay SR which in turn energizes a code determining relay CD for initiating the system and transmitting the code for the selection of the associated field station. The storing relays SR and the code determining relays CD for each of the field stations are arranged to form a bank of relays so interlocked that irrespective of the number of starting buttons SB which are actu ated simultaneously or in rapid succession, resulting in the energization of their corresponding storing relays SR, only one code determining relay CD in the bank may be energized during any one operating cycle. This bank of relays is so arranged that if several storing relays SR are energized at the same time, their corresponding code determining relays CD will be energized successively on successive operating cycles in a predetermined sequence or order determined by the relative location of the code determining relays CD in the bank, which operation has been completely disclosed in the application of Preston et al., Ser. No. 455,304, above mentioned.

The relay CLS is employed for convenience to repeat the code determining relay CD.

A miniature track diagram corresponding with the actual track layout in the territory under the supervision of the operator, is preferably made a part of the control machine and positioned adjacent the control levers for the several field stations. As representative of such a track diagram (see Fig. 1), a portion of track together with a pivoted miniature switch point is is shown as corresponding to the actual track and track switch TS located at the associated field station (see Fig. 2) The position of the track switch TS is indicated upon the track diagram by the movement of the miniature switch point member ts to normal or reverse position, which miniature switch point is preferably actuated by electromagnetic means in accordance with the actual position of the track switch TS as indicated by two indication storing relays 1N and 1N as shown, for example, in my copending application Ser. No. 512,257 filed January 30, 1931.

A correspondence lamp COL is located adja-- cent the switch machine lever SML and is preferably of the telephone switch board type. This correspondence lamp COL has associated therewith a correspondence relay COR which has pickup and stick circuits controlled in accordance with the present invention, and whenever this correspondence relay COR is energized, the correspondence lamp COL is illuminated.

An OS indicating lamp OSL is positioned adjacent the miniature switch point is to indicate, When illuminated, the occupied condition of the detector track section associated with the track switch TS in the field. This lamp OSL is controlled by an indication storing relay IN which is in turn governed by the track relay T through the medium of the communication system.

The indication storing relays 1N 1N and 1N are of the two position polar magnetic stick type having contacts operated to either of two 8X- treme positions in accordance with the polarity of the applied current, with these contacts maintained in such positions until operated to the opposite position by current of the opposite polarity.

The control ofiice equipment includes a battery BT having a center tap connected to the common return line H, for supplying positive and negative potential to the stepping circuit in accordance with the position of the code sending relay CS. Also, a battery ET is provided for supplying energy to the message circuit including the message line wire l3 and the common return line wire 54.

Field station equipment.With reference to the typical field station shown in Fig. 2, a turnout track having rails I? is connected to the main track havig rails I8 by means of a track switch TS. This track switch TS is suitably controlled from one extreme locked position to the other by a suitable type switch machine SM, such for example as shown in the patent to W. K. Howe, Patent No. 1,466,903, dated September 4, 1923, which switch machine is controlled by a switch machine relay SMR subject to the associated signaling system and suitable approach locking means.

The switch machine SM thus remotely controlled by the operator, is preferably provided with a dual control selector, such as disclosed in the application of W. K. Howe, Ser. No. 354,039, filed April 10, 1929, so that a member of a train crew can locally operate the track switch TS for local train movements, as desired, after first obtaining permission from the operator by telephone, or the like.

Signals I and IA serve to govern east bound traffic over the track switch TS onto the main track or the turn-out track respectively; while signals 2 and 2A serve to govern west bound traffic over the track switch TS on the main track or off the turn-out track respectively. These signals l-IA and 2-2A, arranged to control train movements over the track switch TS in the usual way in accordance with recognized practice, are selected in accordance with the position of the track switch TS and a direction relay DR; while their clear or stop indications are dependent upon a signal relay SR and traffic conditions in accordance with the principles of automatic block signal systems, all in a manner as shown and described, for example, in the application of S. N. Wight, Ser. No. 120,423, filed July 3, 1926. Although these signals have been shown as being of the color light type, it is to be understood, however, that they may be of the semaphore type, or any other suitable type railway signal.

The relays SMR, SR and DR, which are controlled over the communication system in accordance with the position of the levers SML and SGL, as more specifically pointed out in the above mentioned application of N. D. Preston, et al., Ser- No. 455,304, are of the polar magnetic stick type and maintain their contacts in the last energized position regardless of subsequent deenergization.

The position of the track switch TS is indicated by the usual switch repeating relay WP which is a polar-neutral type relay energized with a particular polarity in accordance with the position and locked condition of the track switch TS through the usual switch box or point detector mechanism (not shown), but deenergized whenever the track switch is unlocked or in operation. The energization of this relay WP is also governed in accordance with the operated condition of the dual selector, when such a mechanism is employed in conjunction with the switch machine.

The field station is also provided with a change relay CH and a change storing relay CHS. The change relay CE is a quick acting relay being normally energized through either a front or back contact of a neutral contact on the relay WP and such other devices as may have indications to transmit. This relay OH is relatively quick acting with respect to relay WP, so that, when the relay WP is energized or deenergized, the stick circuit for the relay CH is opened sufiiciently long to drop its contacts. The deenergization of the relay CH is further controlled by a stop relay S which is energized on the last step of the operating cycle when the corresponding station is selected and the signals are at stop as controlled by the signal control relay SR. The deenergization of the relay CH energizes the change storing relay CHS which is maintained energized until that station has transmitted indications of the changed condition. The features and mode of operation of such a quick acting change relay in combination with a selector type communication system has been completely disclosed and described in the pending application of DeLong et al., Ser. No. 477,364, filed August 23, 1930.

A track relay T indicates the condition of cocupancy of the detector track section associated with the track switch TS.

It is believed that the nature of the invention, its advantages and characteristic features can be best understood with further description being set forth from the standpoint of operation.

Operation As above mentioned, the system of the present invention has been illustrated as more particularly adapted i or use with a selective duplex coded type communication system as disclosed in the pending application of N. D. Preston et al., Ser. No. 455.304, filed May 24, 1930. In this normally at rest type of communication system, the stepping circuit is normally deenergized, while the message circuit is normally energized for the purpose of providing means by which the field stations may initiate the system into operation.

The series message circuit is normally energized, when the system is at rest, from the positive terminal of battery BT through windings of relay M in the control ofiice, message line wire [3 to the first field station, windings of the relay M at that station, back contact IQ of the relay P, line wire l3 to the remaining field stations, and similarly through the windings of the relays M and contacts of the relays P at those stations, to the common wire [4 at the last field station, and thence to the negative terminal of the battery ET in the control office. This circuit energizes the relays M at the control office and at each field station.

At each field station, as for example the field station illustrated in Fig. 2, the signals liA and 22A normally indicate red or'stop by reason of the position of the signal control lever SGL; while the switch machine SM is usually left in its last operated position, but for convenience is shown in a normal position for the passage of mainline trafiic. With the track switch TS in a normal po ition, suitable point detector contacts or switch box contacts are controlled so as to energize the relay WP with a particular polarity actuating its neutral contacts to energized positions and its polar contacts to right hand extreme positions, as illustrated.

The detector track section associated with the track switch TS is unoccupied by a train, thus allowing the track relay T to be energized as usual in normally closed track circuits.

A change relay CH of the quick acting type is normally energized through a stick circuit including contacts on the various devices which have indications, at intermittent periods, to be transmitted to the control office. In this particular embodiment of the invention, the change relay is shown having its stick circuit associated only with the switch repeating relay WP, the track relay T and the relay S which may be energized only when the signals are at stop. This stick circuit for the relay CH is normally closed from I through front contact 20 of track relay T, wires 2| and 22, front contact 23 of relay WP, wire 24, back contact 25 of relay S, wires 25 and 21, front contact 28 of relay CH, lower winding of relay CH, to

The remaining neutral relays of the communication system are normally deenergized and the magnetic stick type relays are in the positions to which they were operated upon the preceding operating cycle.

Transmission of controls.As previously stated, the operator may at will change the track switch TS from one position to another subject to automatic approach and detector locking means, and may also hold at stop any of the signals, or allow them to clear dependent upon traffic conditions.

To effect traffic movement over the switch, the operator moves the switch machine control lever SML to either a normal or reverse position, as desired, and positions the signal control lever SGL in right or left hand positions for east or west train movement respectively, after which he depresses the starting button SB.

Whenever the switch machine lever SML is operated out of correspondance with the track switch TS in the field, the position of which is indicated by the relays 1N and IN in the control offic'e a pick-up circuit is closed for the correspondence relay COR. For example, when the lever SML is moved to a reverse position and the track switch is indicated as being in a normal position, a circuit is closed from through contact 39 of lever SML, wire 3|, contact 32 of relay IN in a righthand position, wires 33 and 34, lower winding of relay COR, to With the relay COR picked up, a stick circuit is closed from through back contact 35 of relay C wire 36, front contact 31 of relay COR, upper winding of relay COR, to This stick circuit is effective to maintain the relay COR energized until the field station associated with the track switch TS has been registered in the control ofiice resulting in the energization of the relay C Thus, the correspondence lamp COL is illuminated as soon as the relay COR is picked up and is maintained illuminated irrespective of the position of the lever SML so long as the correspondence relay COR is energized. This energizing circuit for the correspondence lamp COL is closed from through front contact 40 of relay COR, wires M and 42, indicator lamp COL, to The manner in which the relay COR is dropped and the lamp COL extinguished, will be explained hereinafter.

The momentary actuation of the self restoring starting button SB closes a pick-up circuit for the storing relay SR from through starting button SB in a depressed position, wires 45 and 46, winding of relay SR, wire 41, back contact 48 of stepping relay 7, to As soon as the contacts of the storing relay SR pick up, a stick circuit is closed from through front contact 49 of .relay SR, wires 44 and 46, winding of storing relay SR, wire 41, back contact 48 of stepping relay f, to

The energization of the storing relay SR results in the energization of its corresponding code determining relay CD in the code determining bank of relays in proper turn, all of which has been more specifically described in the above mentioned application Ser. N. 455,304. It is sufiicient for an understanding of the present disclosure to state that the relay CD is energized in turn in accordance with its position in the code determining bank and remains energized during a cycle of operation of the system for the transmission of the code and controls associated with its corresponding field station. Upon its energization, a circuit is closed for starting the system, as indicated by a legend on the drawings. This starting of the system picks up the cycle controlling relay CC and causes the impulsing relay IR to be intermittently energized for placing time-spaced impulses upon the stepping circuit. The polarity ,of these time-spaced impulses is determined in accordance with the code call of the station to which the controls are to be transmitted and in accordance with the controls which are transmitted to the selected station.

For convenience, the code transmitting means associated with the levers SML and SGL has not been illustrated in detail, as it is believed sufficient to state that the transmission of a station code call results in the selection of that station by causing the energization of its relays SO and TR.

After the selection of the field station, the stepby-step mechanisms at the control office and at the selected field station continue to operate for the transmission of control impulses. Thus, for the second part of the cycle as the step-by-step mechanisms at the selected field station and at the control oiiice continue to operate in synchronism, including relays d, e and also relays 4, 5 and 5, local circuits are closed at the control oifice and at the selected field station. On each of the steps in the control office, the local circuit closed for that step determines the polarity of the impulse for the next step in accordance with the position of the respective control lever; while the polarity of a particular impulse applied to the stepping circuit upon a particular step determines the polarity applied to the local circuit at the selected field station for that step.

The impulses placed upon the stepping circuit cause the operation of the stepping relays irrespective of the polarity of these impulses. As the polarity of the impulses determines the particular control transmitted, the polarity of a particular impulse must be determined in the control ofiice in accordance with the control to be transmitted prior to the actual application of that impulse to the stepping circuit. Thus, the particular polarity of each of the impulses placed upon the stepping circuit for the steps completed by the stepping relays d, e and f, has been shown as determined upon the step preceding its application. More specifically, the polarity of the impulse which effects the picking up of the stepping relays d and 4 is determined through a back contact of the relay (1; the polarity of the impulse which effects the picking up of the stepping relays e and is determined through a front contact of the relay d; and the polarity of the impulse which effects the picking up of relays j and 6 is determined through a front contact of the relay e, and so on for the succeeding steps.

The present embodiment illustrates only three steps which receive controls in accordance with the positions of the levers SML and SGL.

If the switch machine control lever SML is in a normal position, the relay CS is energized from through lever contact 50 in a normal position, wire 5|, front contact 52 of relay CLS, wire 53, control bus 54, back contacts 55, 56 and 51 of relays d, e and 1, wire 58, winding of relay CS, to preceding the application of the first control impulse to the stepping circuit which effects the energization of the stepping relays d and 4. On the other hand, if the switch machine control lever SML is in a reverse position, the relay CS is left deenergized as contact 50 is in its dotted line non-contacting position.

Thus, the code sending relay CS together with suitable polarity selecting. and' storing means (not shown) employed in this type of system causes an impulse of positive or negative character to be placed upon the stepping circuit depending upon whether the switch machine control lever SML is in a normal or a reverse position upon the closing of back contact 63 of the impulsing relay IR.

The stepping circuit is traced from the positive or negative terminal of the battery BT depending upon whether the relay CS is energized or deenergized, through front or back contact 60 of relay CS, wire 6|, front contact 62 of the cycle controlling relay CC, back contact 63 of the impulse relay IR, winding of the line relay U, to the stepping line l2 to the first field station, winding of the line relay L at that station, and similarly through the stepping line l2 to the succeeding field stations, to the common wire I4 at the last field station, and thence to the mid tap of the battery BT in the control oifice. This impulse causes the stepping relays d and 4 to be picked up and at the same time positions the impulse storing relay IS in response to the particular polarity of the impulse placed upon the stepping circuit.

In a similar manner, the control buses 64 and 65 are energized or left deenergized in accordance with the position of contacts 66 and 61 respectively of signal control lever SGL in order to determine the polarity of the stepping impulses for the two succeeding steps. These next two impulses pick up the relays e5 and f6 respectively, while their polarity positions the relay IS for each step.

With the impulse storing relay IS positioned in accordance with the polarity of each of the impulses applied to the stepping circuit, that particular polarity is applied during the deenergization of the stepping circuit between the successive impulses, to the local circuits closed by the stepping relays for actuating the polar relays SMR, DR and SR on their respective steps.

For example, with the relays SO, TR and 4 energized, a circuit is completed upon this first control step for the relay SMR from either (B+) or (B-) depending upon the polarity of the stepping impulse, through polar contact 10 of relay IS in a right or a left hand position, front contact H of relay SO, front contact 12 of relay TR, back contacts 13 and 14 of stepping relays 6 and 5 respectively, front contact 15 of stepping relay 4, winding of relay SMR, to (ON). Current flowing in this circuit from (3+) actuates contacts 16 and 11 of relay SMR to right hand positions; while current flowing from (B) actuates contacts 16 and TI to left hand dotted line positions. With contact 16 in a right hand position, a circuit is closed from through contact 16 in a right hand position, normal operating wire 18, switch machine operating mechanism SM, to but with contact 16 in a left hand position, a circuit is closed from through contact 16 in a left hand position, reverse operating wire 19, switch machine operating mechanism SM, to Thus, the switch machine SM is governed by the control lever SML for operating the track switch TS from one position to another.

In a similar manner, the relays DR and SR are energized with (3+) or (B-) depending upon the polarity of the stepping impulse for the respective steps. Thus, with contact 66 of lever SGL in a left hand position, the relay DR is energized from (B+) on its respective step which actuates contact to a right hand position selecting either the signal I or the signal IA depending upon the position of the switch; while with contact 66 in a central or right hand position, the relay DR is energized from (B) on its respective step which actuates contact 80 to a left hand position selecting either the signal 2 or the signal 2A depending upon the position of the switch. Similarly, with contact 61 of lever SGL in a central position, the relay SR is energized from (3+) on its respective step which actuates contacts 8| and 82 toright hand positions causing the signals l-IA and 2--2A to indicate stop; while with contact 61 in either a right or left hand position, the relay SR is energized from (3-) on its respective step which actuates contacts BI and 82 to left hand positions allowing the particular signal jointly selected by the position of the switch and the direction relay DR to be cleared dependent upon traffic conditions in the usual way.

When the stepping relays at the control office and at the selected station have taken the last step of the cycle (in this case, relays i and 6 picked up), the storing relay SR and the code determining relay CD are dropped by reason of open back contact 48. Also, the cycle controlling relay CC is dropped which stops the impulsing of the stepping circuit by the relay IR.

After the stepping circuit fails to receive impulses for a predetermined period of time the slow acting relays SL and SL drop away which in turn drop the stepping relays at their respective locations. At the selected field station the relays SO and TR are also dropped.

Thus, the system is returned to rest or a period of blank as the time period separating successive cycles is conveniently called.

Transmission of a stop controZ.When the signal lever is in a central or stop position and the starting button SB is depressed for transmitting controls, the relay SR at the corresponding station is actuated, if not already so positioned, so as to place the signals at that station to stop positions. During the same cycle of operation a stop relay S is momentarily actuated, which relay S serves to drop the change relay CH and cause the system to be initiated for the transmission of indications from that field station under certain conditions. This provides that the operator may check the indications of a station without clearing any route or operating any traific controlling device.

For example, if the operator actuates the starting button SB with the system and devices in conditions illustrated, the system is set into operation for the selection of the field station illustrated in Fig. 2 after which the controls, as determined by the existing positions of the control levers SML and SGL, are then retransmitted.

Thus, with the relays SO and TR picked up, the stop relay S is energized on the last step (stepping relay 6 picked up, in this case) as the contact 82 is in a right hand position. The energizing circuit for the relay S is closed from through front contact 83 of relay SO, front contact 84 of relay TR, front contact 85 of stepping relay 6, polar contact 82 of relay SR in a right hand position, winding of relay S, to It is to be noted, that this energizing circuit for the relay S is completed even at the end of a cycle of operation during which the contacts of the relay SR are actuated to stop positions.

After the last impulse of the cycle has been removed from the stepping circuit for a predetermined period of time, the relay SL drops away which drops the relays SO, TR and 6 resulting in the deenergization of the stop relay S. However, the stop relay S is energized sufiiciently long to allow the quick acting change relay CH to drop away by reason of the deenergization of its stick circuit at open back contact 25.

The deenergization of the change relay CH initiates the system into a cycle of operation for the transmission of indications from that field station in a manner presently to be described.

It is to be understood of course that this station must take its turn in transmitting in accordance with the characters of the code calls assigned the remaining field stations of the system, all of which is described in the above mentioned application Ser. No. 455,304.

Transmission of indications.As above mentioned, each field station is capable of automatically initiating the system into operation whenever a device at that station has new indications to transmit; or a-selected field station may be manually controlled to be initiated for the transmission of its indications. in both cases by the deenergization of the change relay CH. In the first case, movement of the This is accomplished contact 20 of the relay T, for example, from one position to the other momentarily opens the stick circuit of the relay CH; while in the latter case, the energization of the relay opens the stick circuit temporarily, as previously explained.

Assuming for convenience that the relay CH has been deenergized, the pick-up circuit for the change storing relay CHS is closed from through front or back contact 20 of the track relay T, wires 2| and 22, through front or back contact 23 of relay WP, wire 24, back contact 25 of relay S,-wires 25 and 27, back contact 23 of relay CH, wire 88, upper winding of the change storing relay CHS, l0 The contacts of the relay CHS are thus picked up closing a stick circuit from through back contacts and 9| of relays SI and TR respectively in multiple, wires 92 and 93, front contact 94 of relay CHS, lower winding of relay CHS, to At the same time the relay CH is energized from through back contacts 90 and Bi of relays SI and TR respectively, wires 92 and 95, front contact 96 of relay CHS, wire 91, upper winding of relay CH, to

The energization of the change storing relay CHS effects the initiation of the system as soon as it passes through a period of rest or a period of blank as sometimes termed.

Such a period of blank occurs after each cycle of operation for the transmission of controls and/or indications and is indicated at each station by the deenergization of the relays SL which permits the pulsing relay P to be picked up through a circuit from through back contact IOI of relay SL, wire I02, front contact I03 of relay CHS, wire HM, lower winding of relay P, to This opens back contact [9 of relay B deenergizing the relays M at each field station and at the control office.

The deenergization of the relay M in the control ofiice closes a starting circuit including back contact I05 of relay M and back contact I05 of relay SL which again initiates the system for transmitting impulses over the stepping circuit by picking up the cycle controlling relay CC and causing the impulsing relay IR to place times-paced impulses upon the stepping circuit, as above explained. -A cycle of operation thus initiated from the field causes impulses to be placed upon the stepping circuit which do not result in the selection of any station unless some control levers in the control oifice have been operated to new positions and the starting buttons for those stations have been actuated thus giving a duplex cycle of operation. For the purpose of considering the present invention it is unnecessary to consider such a cycle of operation, but merely consider that the relays SL at the control o-ifice and at each of the field stations are energized, after which the step-by-step mechanisms at each location sequentially operate in synchronism with the stepping relays in the control o-fiice.

On each of the station registering steps, impulses are transmitted over the message circuit by the energization or deenergization of the pulsing relays P at each of the stations calling in accordance with the code call of those stations in order to register a station in the control office and select that station for transmitting indications. If there is more than one station calling the control ofiice at the same time, the particular station having the most superior code call, as explained in the above mentioned application, Ser. No. 455,304, is registered, but for the purpose of explaining the present invention, it may be assumed that only one station, namely, that illustrated in Fig. 2, is calling the control office. The registration of this station in the control office results in the energization of the station relay C while the selection of the station for the transmission of indications is indicated at that station by the energization of the relays SI and After the selection of afield station and its registration in the control office, the step-by-step mechanisms at the control office and at this field station continue to operate for the transmission of the indication impulses. As these stepby-step mechanisms continue to operate in synchronism, including the stepping relays cl, 6 and f and also relays 4, 5 and 6, local indication circuits are closed both at the selected station and at the control oiiice. On each of the steps, the indication circuits at the field station energize or leave deenergized the relay P which controls the energized condition of the series message circuit extending from the control office through the several field stations. This message circuit includes the message relay M in the control oflice which in turn determines whether positive or negative potential is placed on the indication circuits local to the control oflice.

For example, with the stepping relays d and 4 energized, the relay P is energized, if the track switch TS is in a normal locked position, through a local indication circuit closed from front contact I IQ of relay W P, polar contact I I I of relay WP in a right hand position, wire I I2, front contact I I3 of stepping relay 4, back contacts I I4 and H5 of stepping relays 5 and 6 respectively, wire I I6, front contact I ll of relay TR, front contact I I8 of relay SI, upper winding of relay P, to The energization of the relay P opens back contact I9 thereof and deenergizes the message circuit including the relays M at the control ofiice and at each field station.

On the other hand, if the track switch TS is unlocked or in a reverse position, the energizing circuit for the relay P is not closed on this step, which leaves the message circuit energized.

In the control or'iice, the local indication circuit for this step (relays d and 4 picked up) includes the indication storing relay IN which is energized with current of one polarity or the other in accordance with the energized or deenergized condition of the message circuit. More specifically, with the relays C and d energized, the relay IN is energized with (13+) or (B-) depending upon whether the message circuit is energized or deenergized respectively through front or back contact I29 oi the relay M wire I2I, back contacts I22 and 523 of stepping relays f and 6 respectively, front contact I24 of stepping relay d, indication bus E515, wire I25, front contact I21 of station registering relay C wire I28, windings of relay IN, to (CN). If the track switch is in a normal locked position, the message circuit will be deenergized on this step, which places (B) upon the relay IN and actuates its contacts to right hand dotted line positions; while if the track switch is unlocked or is not in a normal position, the message circuit will be energized on this step which places (13+) upon the relay 1N and actuates its contacts to left hand dotted line positions.

Upon the next step with the stepping relays e and 5 energized, the indication storing relay IN is similarly controlled in accordance with the reverse locked condition of the track switch TS, so that the contacts of the relay 1N will be actuated to right hand positions if the track switch is in a reverse locked position, but will be actuated to left hand positions whenever the track switch TS is unlocked or is not in a reverse position.

Likewise, upon the next step with the stepping relays and 6 energized, the relay IN is controlled in accordance with the condition of occupancy of the detector track section as repeated by the track relay T. If the track section is not occupied, the relay P will be picked up on this step; but if the track section is occupied, the relay P will remain deenergized. Thus, the indication storing relay IN is actuated with (B) or (3+) in accordance with the unoccupied or occupied conditions of the detector track section associated with the track switch TS.

In a similar manner, various additional indications, as may be desired, may be transmitted from the same or difierent stations. It is to be understood, that the indication storingrelays in the control ofiice for each field station are connected through their respective station registering relays to the indication buses I25, I33 and ISI, for example.

With the track switch TS in a normal position, the contacts of the indication storing relays 1N and 1N assume positions, as illustrated, for completing a circuit from (-1-), through contacts I34 and I33 in series, wire I45, to suitable electromagnetic means for actuating the miniature track switch point ts to a normal position; while, with the track switch TS in a reverse position, the contacts or" these indication storing relays are actuated to their dotted line position for completing a circuit from (-1-) through contacts I33 and I34 in series, wire I46, to suitable electromagnetic means for actuating the miniature track switch point is to a reverse position.

Whenever the track switch TS is unlocked and such condition is indicated by the indication storing relays 1N and 1N with their contacts in left hand positions, the miniature switch point is remains in its last operated position, while the correspondence lamp COL is illuminated by means of a circuit from through polar contact I35 of relay IN in a left hand position, wire I36, polar contact I31 of relay 1N in a left hand position, wires I38 and 42, correspondence lamp COL, to

Also, each time indications are transmitted from the field station resulting in the control of the indication storing relays IN, the station registering relay C is necessarily energized which opens back contact 35 included within the stick circuit of the correspondence relay COR. Thus,

if the correspondence relay COR is picked up at i the beginning of such a cycle, and the indication storing relays IN and 1N indicate that the track switch TS is in correspondence with the control lever SML, the relay COR. will be deenergized by reason of open back contact 35, but if correspondence is not existent, the relay COR will remain energized through its pick-up circuit above pointed out.

At the station which is registered in the control ofiice, the relays SI and TR are energized. The change storing relay OHS will then be deenergized by reason of open back contacts and 9| which allows the system to come to rest at the end of the operating cycle, if no other new indications are to be transmitted from this station or any other. On the last step of the operating cycle, the system is brought to rest in the usual way, as above explained, by deenergization of the cycle controlling relay CC.

If the cycle of operation for the transmission of indications wasinitiated by reason of manual control for checking the indications, then the will also be deenergized on the last step by reason of open back contact 48 of stepping relay 1. When the system enters the period of blank and isat rest, theslow acting relays SL aredeenergized at the control office and at each .field station conditioning the system for the transmission of indications and/or controls on the next operating cycle.

Typical combinations of operation-The above description points out in detail how the system may be initiated either manually or automatically for the transmission of controls and the transmission of indications, as well as-pointing out in detail how these controls and indications are stored at the control oflice and at the field stations respectively. Some of the typical combinations of operations that may result-in the normal operation of a centralized traffic control system, as herein contemplated, will be explained.

The most usual operation is that wherein the -operatorestablishes a new route by moving the switch machine lever SML and the signal lever SGL to new positionsand depressing thestarting =button SB which causes the transmission of the desired controls to the relays SMR, DR and SR. The relay SMR in turn causes the switch machine SM to operate the track switch TS to its new position; while the relays DR' and SR determine the route to be cleared after theoperation of the switch.

As previously explained, whenever the switch .machine leverSM'L is operated out of correspond- "ence with the track switch TS, as indicated by-the indication storing relays 1N and 1N the correspondence relay COR is picked up resulting in relay CH and cause the transmission of the indication of the unlocked condition of the track switch; but the switch machine is operating in response to the switch machine relay SMR, so that the contacts I1 and I40 of the relays SMR and WP, respectively, are out of correspondence which completes the stick circuit for the relay CH. Assuming, for example, that the switch is being operated from a normal to a reverse position, the stick circuit for the relay CH is closed from through front contact 20 of the track relay T, wires 2I and MI, polar contact I40 in a right hand position, wire I42, polar contact 11 of relay SMR in a left hand position, wires I43 and 21, from contact 28 of relay CH, lower winding of relay CH, to

Upon the completion of the operation of the track switch TS, the relay WP is energized with the current of opposite polarity in accordance with the new position and locked condition of the switch. This energization of the relay WP actuates its polar contacts to their new positions in correspondence with the polar contacts of the relay 'SMR prior to the actual picking up of the neutral contacts of the relay W-P. "Thus, the

shunt circuit including polar contacts 11 and I40 is opened before back contact 23 is opened and front contact 23 is closed, while movement of the contact 23 from a back to a front position in response to the locking of the track switch TS momentarily opens the stick circuit of the change relay CH causing it to drop its contacts. This results in the initiation of the system and the transmission of the indications of that station in accordance with the new position of the track switch TS.

The registration of this station in the control office energizes the station registering relay C which causes the indication storing relays 1N and IN to be'controlled in accordance with the new position of the track switch TS. As the correspondence indication storing relays are actuated into correspondence with the control lever SML, the correspondence relay COR is deenergizedas well as the indicator lamp COL.

In other words, whenever the switch machine lever SML is operated to a new position and the track switch TS is operated into correspondence therewith, the correspondence lamp COL indicates the lack of correspondence between the switch machine lever SML and the track switch TS until the track switch has been operated into correspondence therewith, but during the unnew position and signal lever SGL is on center at the time the starting button SB is depressed, then the stop relay S at the field station will be picked up during the operating cycle in which the new switch control is transmitted, but the shunt circuit completed by the contacts 11 and I 48 of relays SMR and WP respectively, also shunts outback contact 25 of relay S, thus eliminating an unnecessary cycle of operation of the communication system. On the other hand, if the signal lever SGL is in a position to cause a clearing of a particular signal, the stoprelay S will of course not be picked up.

If the switch machine SM becomes stalled in mid-stroke due to ice on the switch points, or some other similar reason, the operator may return the switch machine lever SML to its former position and reverse the switch machine returning the track switch TS to its former position. Under such conditions, the polar contacts of the relay SMR are returnedinto correspondence with the polar :contacts of the relay WP so that when the track switch TS reaches its former locked I transmission of such indications drops the correspondence relay COR and the correspondence lamp COL is not illuminated.

If .for some reason the switch machine'becomes stalled in mid-stroke and fails to return to its former position, the operator may check the position of the track switch by depressing the starting button SB. As the polar contacts of the relay SMR and relay WP are now in correspondence, because the lever SML has been returned to its former position, the transmission of the controls with the signal lever SGL in itsstop .positicmthe stop relay S will be picked up and drop the change relay CI-I resulting in the transmission of the indications from that station.

With the track switch TS in an unlocked stalled condition, the indication storing relays 1N and IN will have their contacts actuated to left hand positions closing the circuit through contacts I31 and 135 respectively for the indicator lamp COL, which tells the operator that the track switch TS is actually unlocked. Under these conditions the correspondence relay COR is dropped but this is immaterial as contacts I31 and I35 of relays IN and 1N are suflicient to energize the lamp COL.

Under normal conditions the track switch TS is in correspondence with the switch machine lever SMLso that the polar contacts 11 and Me of the relays SMB and WP are in correspondence. Then, if the track switch TS is operated by hand to a new position by cranking the switch machine, the relay WP will be deenergized while the track switch is unlocked and the indications of such condition will be transmitted because of the deenergization of the change relay CH as a result of the movement of the contact 23 from a front to a back position. Also, upon the locking of the track switch by the completion of such hand operation back to the original position, the system will be again initiated and the indications transmitted.

In the control office, when the track switch is unlocked due to hand operation, the indication storing relays 1N and IN will indicate such a condition and illuminate the correspondence lamp COL through polar contacts I31 and I35 in left hand positions; while the miniature track switch point is will remain in its former position. When the track switch assumes its new locked position, by reason of hand operation, the indication storing relays will indicate such new position causing the miniature track switch point ts to be operated into correspondence with the track switch TS, if the starting button SB is actuated and the indications are thereby checked but, as the switch machine lever SML is not in correspondence with the track switch TS, the pick-up circuit for the relay COR will be completed thereby continuing the energization of the correspondence lamp COL through front contact 46. The indicator lamp COL will remain illuminated unless the operator moves the switch machine lever SML into correspondence with the hand operated position of the track switch and depresses the starting button SB so as to check the indications at the field station, which check will then indicate the track switch to be in correspondence with the lever SML.

However, when the track switch TS is operated by hand, it is usual for the operator to leave the lever SML out of correspondence with the track switch TS because the train crew, which operated the track switch, are usually required to return it to its orginal position; and during the interim the illumination of the lamp COL reminds the operator that the track switch TS is being operated by hand.

The system is not automatically initiated into operation for the transmission of indications by the deenergization of the relay CH upon the track switch TS assuming a new position when cranked to that new position because the polar contact I45 of the relay WP assumes a position out of correspondence with the polar contact ll of the relay SMR before the contact 23 assumes a picked up position, thereby completing a shunt circuit for the contact 23, as previously explained. On the other hand, providing the operator has not moved the control lever SML, upon the return of the track switch TS to its original position by a hand cranking operation, the system is automatically initiated because the contact I assumes a position in correspondence with the contact 11 prior to the picking up of the contact 23, so that the contact 23 is not shunted when it picks up thereby causing a momentary deenergization of the relay CH and the initiation of the system for the transmission of indications as above described. In other words, when the track switch TS is locally hand operated, an indication is given to the operator that it is out of correspondence with the control lever SML but such indication is removed as soon as the track switch is returned to its original position even though the operator does nothing in the mean- A system of centralized trafiic control has thus been described in which the indications of the condition of a railroad track switch have been adequately and advantageously displayed for the information of an operator at a central point, while these indications have been transmitted over a selective type communication system in a manner to reduce the number of operating cycles usually required for the accurate informing of the operator. The present invention has also provided that the operator may have adequate control over the trafiic controlling devices at all times and may be able to manually check the indications at such stations as he may desire providing that the signals at such stations are at stop. With the signals at stop at such stations where the indications are checked, a change in the control conditions, due to the forgotten movement of some lever, cannot then result in any harmful or undesirable conditions at the field station. In other Words, the checking of indications has been put in the hands of the operator in such a way as to be entirely safe.

Having described a centralized traffic control system for railroads as one specific embodiment of the present invention. it is desired to be understood that this form is selected to facilitate in the disclosure of the invention rather than to limit the number of forms which it may assume; and, it is to be further understood that various modifications, adaptations and alterations may be applied to the specific form shown to meet the requirements of practice, without in any manner departing from the spirit or scope of the present invention except as limited by the appended claims.

What I claim is:-

1. In a centralized trafiic control system for railroads, a track switch, a switch machine for operating said track switch, indication storing means for indicating the normal or reverse position of said track switch, said indication storing means being intermittently controlled in accordance with the position of said track switch through the medium of a code type communication system, a control lever for governing said switch machine, a stick relay having a pick-up circuit closed Whenever said control lever is operated out of correspondence with said track switch as indicated by said indication storing means, a stick circuit for said stick relay closed only between the intermittent control of said indication storing means, and a correspondence lamp illuminated when said stick relay is picked up.

2. In a centralized trafiic control system for railroads, a track switch, a switch machine for operating said track switch, a control lever for governing said switch machine, indication storing means only momentarily actuated upon each operation of said track switch to a new position, a stick relay picked up whenever said control lever is operated out of correspondence with said track switch as indicated by said indication storing means and maintained picked up until a subsequent actuation of said indication storing means irrespective of the movement of said control lever, and indicator means governed by said stick relay.

3. In a centralized trafiic control system for railroads, a track switch, a switch machine for operating said track switch, a control lever for governing the operation of said switch machine, indication means for indicating the position and locked condition of said track switch, a stick relay picked up when said control lever is operated out of correspondence with said track switch, means dropping said stick relay only when said indication means receives a new indication, and a correspondence lamp illuminated when said stick relay is picked up, whereby said correspondence lamp is illuminated whenever said control lever has been operated out of correspondence with said track switch and is maintained illuminated irrespective of the subsequent movement of said control lever until said indication means receivesa new indication.

4. In a centralized trafiic control system for railroads, a control oifice, a plurality of field stations, a station selective type communication system connecting said control ofiice with said field stations, a track switch at each field station, a switch machine at each field station for operating said track switch at that field station, control levers in the control ofiice for'governing the operation of each of said switches, indication means in the control office at times governed over said station selective type of communication system in accordance with the position of their respective track switches, means registering the lack of correspondence between a particular control lever and its track switch in accordance with said indication means until said indication means is again governed by that track switch, and a correspondence lamp in the control office for each of said track switches governed both by its corresponding indication means and by its corresponding means for registering the lack of correspondence of said control lever with its track switch.

5. In a centralized traffic control system for railroads, a control oilice, a field station, a track switch at said field station, manual control means for governing operation of said track switch, indication storing means in the control ofiice for being selectively governed in accordance with said track switch, communication means both manually and automatically initiated for causing said indication means to be selectively governed, and

means for preventing either manual or automatic initiation of said communication means when said manually controlled means is out of correspondence with said track switch.

6. In a centralized traflic control system for railroads, a control office, a field station, a track switch at said field station having signals governing trafiic thereover, manually controlled means for governing operation of said track switch and for causing said signals to display proceed or stop indications, indication storing means in the control oifice for being selectively governed in accordance with the condition of said track switch, communication means for selectivelygoverning when initiated said indication storing means, and means for manually initiating said communication'means only when said manually controlled means is causing said signals to display stop indications.

7. In a centralized trafiic control system for railroads, a track switch, a switch machine for operating said track switch, manually controlled means for governing operation of said switch machine, indication storing means selectively governed by said track switch, means selectively governing said indication storing means only when said track switch is operated to a new position into correspondence with said manually controlled means, correspondence means registering a lack of correspondence between said manually controlled means and said track switch until said indication storing means is selectively governed, and a correspondence lamp illuminated when said correspondence means is registering a lack of correspondence.

8. In a centralized trafiic control system for railroads, a control o-flice, a field station, a track switch at said field station, a switch machine for operating said track switch, a control lever in the control oifice for governing operation of said switch machine, indication storing means in the control office governed in accordance with the position of said track switch, a normally at rest communication system for establishing communication between said control oflice and said field station, means in the control oifice for manually initiating said communication system, means at the field station for automatically initiating said communication system only when said track switch is operated to a new position into correspondence with said control lever, and correspondence means registering a lack of 'correspondence between said manually controlled lever and said indication storing means until said indication storing means is again controlled in accordance with the condition of said track switch.

9. In a centralized traflic controlling system for railroads, a traffic controlling device, a lever for manually governing operation of said device, two indication responsive relays one assuming aparticular position when said device assumes one condition and the other relay assuming such particular position when said device assumes another condition, a two position indicator operated by said two relays, and a second indicator rendered active only if neither of said relays assumes said particular position or if said lever is out of correspondence with said trafiic controlling device.

I 10. In a centralized traflic controlling system, the combination with a distant track layout including a track switch, a power operated switch machine for operating said track switch, a selector system of the normally at rest code type for controlling said switch machine from a local point and for transmitting to said local point an indication of its position and including a circuit which if momentarily opened initiates said system, a switch machine control relay for controlling said switch machine and controlled over said selector system, and contacts associated with said control relay and switch machine opening said circuit momentarily and only when said switch machine has completed an operating stroke.

11. In a centralized trafiic controlling system, the combination with a distant track layout including a track switch, a power operated switch machine for operating said track switch, a selector system of the normally at rest code type for controlling said switch machine from a local point and for transmitting to said local point an indication of its position and including a circuit which if momentarily opened initiates said system, a switch machine control relay for controlling said switch machine and controlled over said selector system, contacts associated with said switch machine momentarily opened upon initiation and completion of an operating stroke and included in said circuit, and a branch circuit for shunting said contacts and closed only if said control relay and said switch machine assume non-corresponding positions.

12. In a centralized trafiic controlling system, the combination with a distant track layout including a track switch, a power operated switch machine for operating said track switch, a selector system of the normally at-rest code type for controlling said switch machine from a local point and for transmitting to said local point an indication of its position and including a circuit which if momentarily opened initiates said system, a switch machine control relay for controlling said switch machine and controlled over said selector system, contacts associated with said switch machine momentarily opened upon initiation and completion of an operating stroke and included in said circuit, a signal associated with said track switch, contacts associated with said signal and opened momentarily when said signal is operated to stop, and a branch circuit for shunting said contacts associated with said track switch and said contacts associated with said signal and closed only if said control relay and switch machine assume non-corresponding positions.

13. In combination, a track switch, a power driven switch machine for operating said track switch, a control relay for governing the operation of said switch machine, indication means, a

normally at-rest communication system for at times governing said indication means in accordance with the position of said track switch when said communication system is initiated into operation, manually governable means for initiating said communication system into operation, automatically governable means for initiating said communication system into operation, and means for preventing initiation of said communication means by either said manually governable means or said automatically governable means when said control, relay and said track switch are out of corresponding positions.

14. In a centralized traffic controlling system for railroads, a control ofiice, a field station, a track switch at said field station having signals governing traffic thereover, manually controlled means for governing operation of said track switch and for causing said signals to display proceed or stop indications, a code type communication means interconnecting said control office and said field station for at times transmitting indications when initiated, indication storing means in the control oflice selectively governed in accordance with the condition of said track switch through the medium of said code type communication means, and means for manually initiating said communication means for the governing of said indication storing means only when said manually controlled means is causing said signals to display stop indications and said track switch and its said manually controlled means are in corresponding positions.

15. In combination, a track switch, a switch machine for operating said track switch, a free and non-lockable control lever for governing the operation of said switch machine, indication means, a selector type communication system for at times jointly controlling said indication means in accordance with the position of said track switch and said switch machine, means distinc tively controlled when said control lever is out of correspondence with said track switch and said switch machine as indicated by said indication means, and other means for maintaining the distinctive condition of said means until said indication means is again controlled through the medium of said selector type communication systern.

16. In combination, a railroad track switch, a switch machine for operating said track switch, a control lever for governing the operation of said switch machine, indication storing means momentarily actuated through the medium of a selector type communication system upon each operation of said track switch to a new position, a stick relay, a picked up circuit for said stick relay closed whenever said control lever is out of correspondence with said track switch as indicated by said indication storing means, a stick circuit for said stick relay maintained closed irrespective of said control lever until a subsequent actuation of said indication storing means, and means governed by said stick relay.

1']. In combination, a switch machine for operating a railroad track switch, electro-magnetic control means for said switch machine, a polarneutral relay controlled in accordance with the position and locked condition of the track switch, a normally at-rest selector type communication system for transmitting indications of the position and locked condition of the track switch as repeated by said polar-neutral relay when such system is initiated into operation, a normally energized stick relay for initiating said selector system when deenergized, a stick circuit for said stick relay including its own front contact and a front-back neutral contact of said polar-neutral relay, whereby operation of said front-back neutral contact momentarily opens said stick circuit,

a branch circuit for shunting said front-back neutral contact including a polar contact of said polar-neutral relay and a contact of said electro-magnetic means, closed whenever said electro-magnetic control means and said polar-neutral relay are out of corresponding positions, and a pick-up circuit for said stick relay momentarily closed whenever said system has been initiated for the transmission of said indications.

18. In combination, a station selective code type communication system, a switch control lever for governing the operation of a distant track switch through the medium of said communication system, electro-magnetic means positioned in accordance with the position and locked condition of the distant track switch through the medium of said communication system, a station registration relay picked up whenever said electro-magnetic means is to be governed, a correspondence relay picked up whenever said switch control lever is out of correspondence with the position of the distant track switch as indicated by said electro-magnetic means, a stick circuit for said correspondence relay including its own front contact and a back contact of said station registration relay, and an indicator lamp energized whenever said electromagnetic means indicates the unlocked condition of the distant track switch and whenever said correspondence relay is picked up.

19. In a centralized traffic control system, a power-operated switch machine, a control panel in the. central oflice, a manually operable lever on said panel governing the operation of said switch machine, indicating means in the control oflice responsive to the position and locked condition of said switch machine, and a visual indicator on said panel associated with said lever and jointly controlled by said lever and said indicating means, means for automatically displaying said indicator whenever said lever and said indicating means assume non-corresponding positions and maintaining said indicator once displayed in that condition until said indicating means is subsequently actuated to correspond with the existing position of said lever.

20. In a system of centralized traflic control, means for controlling and indicating a poweroperated switch machine comprising, a control lever, indicating means governed over line wires in accordance with the position of the switch machine in the field, a stick relay controlled by said lever and said indicating means, said stick relay automatically assuming a given condition whenever said lever and said indicating means assume non-corresponding positions, said stick relay remaining in said given condition until said indicating means is subsequently operated into correspondence with the then existing position of said lever, and a visual indicator associated with said lever and displayed while said stick relay is in said given condition.

21. In a centralized trafiic control system of the code communication type, a power-operated switch machine, a lever in a control oflice for governing the operation of said switch machine, indicating means in the control oifice automati- 'cally positioned by a series of impulses over line wires in accordance with the normal or reverse position of said switch machine, a stick relay having a pick-up circuit energized whenever said lever and said indicating means assume non-correspondingpositions, a stick circuit for maintaining said relay energized until a series of impulses are subsequently transmitted to operate said indicating means, and a visual indicator associated with said control lever and displayed while said stick relay is energized.

"22; In a centralized trafiic control system, the combination with a power-operated track switch and a control lever therefor in a central oflice, of means for indicating in the control ofiice the condition of said switch for the information of the operator comprising, indication registering relays at times operated by impulses over line wires in accordance with the position and locked condition of said track switch, said indication registering relays closing contacts when said switch is locked normal or reverse or unlocked respectively, an out-of-correspondence lamp, a circuit for lighting said lamp if the contacts of said indication registering relays are closed for the unlocked condition of the track switch, and means including a stick relay for lighting said lamp whenever said indication registering relays and the position of said control lever do not correspond and for maintalning said lamp lighted until impulses are subsequently transmitted to condition said registering relays into correspondence with the then existing position of said control lever.

23. In a centralized trafiic control system of the normally at-rest code communication type, means for initiating operation of said system at a field location to transmit indications of the condition of a power-operated track switch at such station comprising, a control relay for said switch, a neutral-polar switch position repeating relay governed in accordance with the position and; locked condition of said switch, a circuit for starting the communication system when momentarily opened, said circuit including front and back contacts in multiple of the neutral armature of said repeating relay, and a shunt for said contacts closed whenever said control relay and said repeating relay are in non-corresponding normal or reverse sitio'ns.

24. In a centralized traffic control system employing a communication system of the multiple impulse type, the combination with a power-operated switch machine and a control relay therefor, a neutral-polar switch position repeating relay governed in accordance with the position and locked condition of said switch machine, said re.- peater rel'aybeing energized with onepolarity' or the other when the switch machine is locked in a normal or reverse positions respectively and being deenergized when said switch machine is unlocked, means tending to initiate operation of said communication system upon movement of the neutral armature of said repeating relayto either position, and means for preventing such initiation if at the time of such movement of said armature said control relay for the switch machine and the polar contacts'of said repeating relay are not in corresponding positions. I

25. In a centralized traffic control system, a normally at rest communication system of the multiple impulse type, means for initiating operation of said system at a field location upon completion of the operation of a power-operated switch machine comprising, a neutral-polar switch position repeater relay energized with one polarity or the other when switch machine is locked normal or reverse and deenergized when saidswitch'machine is unlocked, a starting circuit broken by movement of the neutral armature of said repeating relay, and means for maintaining said circuit closed while said control relay and said repeater relay are not in corresponding normal or reverse conditions.

- 26. In a centralized trafilc control system for railroads, a power-operated switch machine at a field station, a manually operable control lever in a control oflice governing said switch machine, indication means in the control ofiice, a communication system of the multiple impulse type including line wires extending from the control office' to the field station for operatively connecting said switch machine with said control lever and also said indication means, said communication system acting to operate said indicati'on means to positions in accordance with the locked position of said switch machine, and means in the control ofiice manifesting lack of correspondence between said control lever and said indication means, said manifesting means being initiated upon movement of said control lever and remaining effective until said indication means is again controlled by said communication system.

27. In a centralized trafiic control system of the multiple impulse type including line wires extending from a control oflice to a field station, a power-operated switch machine at the field station, a manually operable control lever in the control oflice for said switch machine, indication means in the control office at times governed by impulses on said line wires in accordance with the locked position of said switch machine, means in the control office manifesting lack of correspondence between said control lever and said indication means and remaining active when once operated until said indication means is again governed over said line wires, and a correspondence lamp associated with said control lever and lighted by said manifesting means when active.

28. In a centralized traffic control system, a power-operated switch machine, a control lever for said switch machine, electro-responsive means for indicating the position and locked condition of said switch machine, means including line wires for operating said electro-responsive means by the character of impulses applied to said line wires in accordance with the condition of said switch machine, means manifesting lack of correspondence between said control lever and said electro-responsive means, said manifesting means being initiated upon movement of said control lever and remaining effective until said electro-responsive means is again operated by impulses over said line wires, and a visual indicator associated with said control lever and displayed by said manifesting means when effective and also displayed by said electro-responsive means when indicating the unlocked condition of said track switch.

29. A centralized traffic control system including a communication system which acts to transmit controls and indications by the character of impulses applied to line wires extending from a control office to a field station and comprising, a trafiic controlling device at the field station, a manually operable control lever in the control office for governing said device through the medium of said communication system, and visual indicating means in the control office governed by indications transmitted by said communication system and automatically displayed whenever said control lever is out of correspondence with the last indicated condition of said trafiic controlling device, said indicating means when once displayed remaining in that condition irrespective of movement of said control lever until said communication system again operates to transmit indications of the then existing condition of said trafiic controlling device.

30. A centralized traffic controlling system including a communication system acting to transmit controls and indications by the character of impulses applied to line wires connecting a control oflice and a field location, and comprising, a power-operated switch machine at the field station, a manually operable control lever in the control ofiice for governing said switch machine through the medium of said communication system, and means in the control office including a visual indicator and automatically governed by indications of the position and locked condition of said switch machine transmitted by said communication system, said means acting to display a visual indication whenever said control lever is out of correspondence with the last indicated locked position of said switch machine and also whenever said switch machine is indicated as unlocked, said means when once rendered effective remaining in that condition irrespective of movement of said control lever until an indication of the locked position of said switch machine is transmitted by said communication system to conform with the existing position of said control lever.

31. A centralized traflic control system for controlling a switch machine at a distant field station from a control office and indicating in the control ofiice the condition of said switch machine comprising, in combination with a communication system of the multiple impulse type for transmitting controls and indications over line wires connecting the control ofiice and the field station, a control lever in the control office for governing the operation of said switch machine, indicating means controlled by said control lever and by said communication system and automatically rendered active whenever said control lever is in a position out of correspondence with the last indicated position of said switch machine, said indicating means when once rendered active remaining in that condition until new indications of the position of said switch machine are transmitted by said communication system even though the lever is restored to its former position, and a lamp associated with said lever and lighted by said indicating means when active.

32. In a centralized traffic controlling system of the normally at-rest code communication type for transiniting controls and indications to and from a power operated switch at a field station, means at the field station for initiating operation or the system to transmit indications to a control office comprising, a neutral-polar switch position repeating relay governed in accordance with the position and locked condition of the power operated track switch, a normally energized circuit for starting the communication system into operation when momentarily opened, multiple front and back contacts of said neutralpolar relay included in series in said circuit, and a contact manually governable through the medium of the communication system included in series in said circuit for momentarily opening said circuit when such contact is operated.

33. In a centralized traffic controlling system of the normally at-rest code communication type for transmitting controls and indications to and from a power operated switch at a field station, means at the field station for initiating operation of the system to transmit indications to a control office comprising, a neutral-polar switch position repeating relay governed in accordance with the position and locked condition of the power operated track switch, a contact at the field station manually governable from the control office through the medium of the communication system, a change relay at the field station for starting the communication system into operation when de-energized, and a stick circuit for said change relay including multiple front and back contacts of said neutral-polar relay and said manually governable contact, whereby indications of the position and locked condition of the track switch are transmitted over the communication system in response to either a change in condition of the track switch or a manual act in the control ofiice.

34. In a centralized trafiic controlling system of the normally at-rest code communication type for transmitting controls and indications to and from a power operated switch at a field station, means at the field station for initiating operation of the system to transmit indications to a control office comprising, a neutral-polar switch position repeating relay governed in accordance with the position and locked condition of the power operated track switch, a contact manually governable from the control office through the medium of the communication system, a change relay for starting the communication system into operation when de-energized, a normally energized stick circuit for said change relay including front and back contacts of said neutral--polar relay and said manually governable contact, whereby indications of the position and locked condition of the track switch are transmitted over the communication system in response to either a change in condition of the track switch or a manual act in the control oflice, and a pickup circuit for said change relay closed only momentarily following the dropping away of said change relay while said communication system is at rest.

35. In a centralized trafiic controlling system of the normally at-rest code communication type for transmitting controls and indications between a control office and a field station, a plurality of devices at the field station for receiving controls and having indications to transmit, means at the field station effective to automatically initiate the communication system to transmit the indications from the field station when one of said devices changes its condition, and means at the station rendered effective only in response to a particular control received over the communication system to initiate the communication system for the transmission of indications from that particular station.

36. In a centralized trafiic controlling system of the normally at-rest code communication multiple impulse type connecting a control ofiice and a field station, a plurality of devices. at the field station having indications to transmit to the control office, means at the field station eiTective to automatically initiate the communication system to transmit the indications when any one of said devices changes its condition, and means at the field station rendered efiective only in response to the composite characteristics of a particular combination of impulses received over the communication system to initiate the communication system for the transmission of indications from that particular field station,

3'7. In a centralized trafiic controlling system of the normally at-rest code communication multiple impulse type, a normally de-energized control line circuit connecting a control office and a field station, means at the control office for impressing different series of impulses on said control line circuit, means at the field station distinctively responsive to said difierent series of impulses, a plurality of devices at the field station, an indication line circuit connecting the control oifice and the field station, indication transmitting means at the field station effective when set into operation to distinctively condition said indication line circuit for a series of impulses in accordance with the condition of said devices, means at the control ofiice distinctively responsive to said distinctive conditioning of said line circuit, means responsive to a change in any one of said devices to set said indication transmitting means into operation, and means re- Sponsive only to a particular series of impulses received over said control line circuit to set said indication transmitting means into operation.

38. A centralized traflic controlling system comprising, a normally at-rest code type communication means for transmitting indications of a power operated track switch to a control ofiice, means for initiating operation of said communication means to transmit indications to the control oflice, a switch position repeating relay controlled only in accordance with the position and locked condition of the power operated track switch, a contact manually controllable from the control ofiice through the medium of said communication means, and a normally energized starting circuit for setting the communication means into operation When momentarily deenergized, said circuit including said contact in series with front and back contacts of said switch position repeating relay arranged in multiple.

39. A centralized traflic controlling system com prising, a normally at-rest code type communi cation means for transmitting indications from a field station to a control oifice, a normally energized change stick relay acting when deenergized to initiate operation of said communication means, a normally energized stick circuit for said change relay, means responsive only to the composite character of a particular code combination of impulses transmitted by said communication means from the control ofiice to the field station for momentarily opening said stick circuit of said change relay.

NEIL D. PRESTON.

DISCLAIMER 2,038,128.Neil D. Preston, Rochester, N. Y. CENTRALIZED TRAFFIC CONTROLLING SYSTEM. Patent dated April 21, 1936. Disclaimer filed October 23, 1937, by the assignee, General Railway Signal Company.

Hereby enters the following disclaimer: Disclaims from claim 26 any system, except wherein the means in the control oflice manifesting lack of correspondence between said control lever and said indicating means is initiated by the movement of the lever to a different position alone and regardless of any subsequent operation of the code communication system, and wherein said means manifesting lack of correspondence if once initiated remains in that condition regardless of any subsequent change in the position of the lever and until said indicating means is again actually operated by the code communication system.

Hereby disclaims claims 35 and 36.

[Ofiicial Gazette Noeember 9, 1937.] 

